Integrated-optical chemical and biochemical sensor

Abstract

The integrated-optical chemical and/or biochemical sensor comprises a resonant waveguide structure (1). A chemical and/or biochemical substance (2) to be sensed can be deposited on a surface of the waveguide structure (1). Incident light (31) is coupled into the waveguide structure (1) by a grating structure (G), making use of a first set of degrees of freedom. The incoupled light (32) interacts with the substance (2), which emits fluorescent light (42). Fluorescent light (42) is coupled out by the same grating structure (G), making use of a second set of degrees of freedom which differs from the first set of degrees of freedom in at least one degree of freedom. For example, the incident light (31) is coupled in using a first diffraction order mg,ex=1, and the emitted (42) light is coupled out using a second, different diffraction order mg,em=2. By this measure, the emitted outcoupled light (43) is clearly separated from exciting light (33) which is reflected and/or coupled out using the first diffraction order mg,ex=1. Such a clear separation increases the signal-to-noise ratio of the sensor signal.

What is claimed is:  
     
       1. An integrated-optical chemical and/or biochemical sensor comprising: 
       a resonant waveguide structure;  
       means for at least temporarily depositing a chemical and/or biochemical substance to be sensed on a surface of said resonant waveguide structure;  
       means for irradiating said substance with first electromagnetic radiation and for causing said substance to interact with said first electromagnetic radiation in such a way that it emits second electromagnetic radiation which differs in at least one parameter from said first electromagnetic radiation and excites a resonant electromagnetic field in said resonant waveguide structure;  
       a circular grating structure for coupling out said second electromagnetic radiation from said resonant waveguide structure, said circular grating structure being such that the outcoupling process differs from the irradiating process in the diffraction order, the polarization, the guided-mode order, the grating vector and/or the degree of resonance; and  
       means for detecting second electromagnetic radiation exiting from said resonant waveguide structure.  
     
     
       2. The sensor according to  claim 1 , wherein said irradiating means comprise a grating structure. 
     
     
       3. The sensor according to  claim 2 , wherein said irradiating grating structure (G) is identical with said outcoupling circular grating structure. 
     
     
       4. The sensor according to  claim 1 , wherein said outcoupling circular grating structure is a focusing circular grating structure. 
     
     
       5. The sensor according to  claim 1 , wherein said irradiating means comprise a grating structure making use of a first diffraction order, and wherein said outcoupling means comprise a grating structure making use of a second diffraction order which is different from said first diffraction order. 
     
     
       6. The sensor according to  claim 1 , wherein said irradiating means are for irradiating said substance with electromagnetic radiation at a first polarization, and wherein said outcoupling means are for coupling out electromagnetic radiation at a second polarization which is different from said first polarization. 
     
     
       7. The sensor according to  claim 4 , wherein said irradiating means are for exciting an electromagnetic guided wave, having a first mode order in said resonant waveguide structure, and wherein said circular grating structure is for coupling out an electromagnetic guided wave having a second mode order, which is different from said first mode order, from said resonant waveguide structure. 
     
     
       8. A one-or two-dimensional array of sensors according to  claim 1 . 
     
     
       9. A method for integrated-optically sensing a chemical and/or biochemical substance using a resonant waveguide structure, comprising the steps of: 
       at least temporarily depositing said chemical and/or biochemical substance on a surface of said resonant waveguide structure;  
       irradiating said substance with first electromagnetic radiation;  
       causing said substance to interact with said first electromagnetic radiation in such a way that it emits second electromagnetic radiation which differs in at least one parameter from said first electromagnetic radiation;  
       causing said second electromagnetic radiation to excite a resonant electromagnetic field in said resonant waveguide structure;  
       coupling said second electromagnetic radiation out from said resonant waveguide structure such that the outcoupling process differs from the irradiating process in at least one of a diffraction order, polarization, guided-mode order, grating vector and degree of resonance, said second electromagnetic radiation being coupled out from said resonant waveguide structure by a circular grating structure; and  
       detecting second electromagnetic radiation.  
     
     
       10. The method according to  claim 9 , wherein the interaction of said substance with said first electromagnetic radiation comprises luminescence, scattering, absorption, chemiluminescence and/or electrochemiluminescence. 
     
     
       11. The method according to  claim 9 , wherein said first electromagnetic radiation is coupled into said resonant waveguide structure by a grating structure making use of a first diffraction order, and wherein said second electromagnetic radiation is coupled out from said resonant waveguide structure by a circular grating structure making use of a second diffraction order which is different from said first diffraction order. 
     
     
       12. The method according to  claim 9 , wherein said first electromagnetic radiation has a first polarization, and wherein said second electromagnetic radiation has a second polarization which is different from said first polarization. 
     
     
       13. The method according to  claim 9 , wherein said first electromagnetic radiation excites an electromagnetic guided wave, having a first mode order, in said resonant waveguide structure, and wherein said second electromagnetic radiation excites an electromagnetic guided wave, having a second mode order which is different from said first mode order, in said resonant waveguide structure.